The development of neuromuscular junctions will be studied in vivo and in tissue and organ culture. The rate of synapse formation will be measured. The trophic effects of innervation will be studied to determine their mechanism. The requirements for synaptogenesis will be examined using specific probes for membrane components. These will include neurotoxins, lectins, sugar and nerve specific antibodies and anti-receptor antibodies. Synaptogenesis between cloned cell lines will be studied as a model system. The defect in myasthenia gravis will be investigated. The effect of anti-receptor antibody on receptor function will be investigated by means of acetylcholine noise analysis. The effect of antibody on receptor turnover will be measured. The use of muscle cultures as diagnostic assays will be investigated.